The primary purpose of this project is to examine the relationship between hypnotic susceptibility and mental imagery. Previous research has suggested a correlation between hypnotizability and subject variables related to mental imagery vividness or absorption. However, this research has relied on self-ratings of imagery. The present project will use an objective laboratory measure of mental imagery absorption. Groups of highly hypnotizable and low hypnotizable subjects will be selected in preliminary screening. The selected subjects will then be tested on a psychophysical task, without hypnosis. On some trials of this visual signal-detection task the subjects will be instructed to concentrate on mental images of certain specified objects. Previous research has shown that concurrent mental imagery interferes with signal detection. The rationale of this project is that the amount of interference is a measure of the subjects degree of absorption in mental imagery, and we predict that this measure will be positively related to the subjects' hypnotizability scores. A second purpose is to conduct a pilot study on the effect of hypnosis on imagery absorption, as measured in the signal-detection task. This project will have implications for understanding the nature of mental imagery, the nature of hypnosis, and subject variables related to hypnotizability. The latter may lead to the development of procedures for increasing hypnotizability, which would increase the proportion of patients who could benefit from clinical hypnosis.